The present invention relates to a printer comprising a print unit, a supply unit for holding a web of receiving material wound into a roll, and a system for unwinding the web and transporting it for printing to the print unit, which supply unit is adapted to carry an elongated member on which the roll is fixed substantially concentrically. The present invention also relates to a supply unit for holding the receiving material and an elongate member comprising elements for releasable fixing of the receiving material.
In one embodiment of a known printer, a roll of the receiving material is fixed, frequently prior to the placing of the roll in the supply unit, on an elongated member, particularly a cylindrical core, which can be received in bearer elements adapted for this purpose in the supply unit. To unwind the web, the core is rotatably accommodated in the bearer elements. During printing of the receiving material, the required quantity of material is unwound at a time from the roll and the web thus unwound is fed for printing to a print unit, for example an inkjet printhead.
After the web of receiving material has been completely unwound, the core is provided with a new roll of receiving material so that further printing operations, starting from the same position in the supply unit, can take place. Rolls of different widths can be fixed on the core. The advantage of this is that on the basis of one core co-operatively connected to the bearer elements in the supply unit, it is possible to accommodate rolls of different widths in the supply unit. Since rolls of different widths can be fixed on the core, it is advantageous to accurately position such a roll with respect to a reference position on the core. As a result, prior to the unwinding of the web, it is known where the web is situated with respect to the print unit. This simplifies the transport and positioning of the web in the printer.
A known method of positioning the web is placing the roll against a stop, for example a flange, provided on the core. The disadvantage of this method is that the center of the roll does not normally coincide with the center of the printer. To solve this problem it has previously been proposed to position each roll on the core by the use of a movable indication in the supply unit of the printer, the position of such indication corresponding to the width of the roll. This method is complex and prone to faults.